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IM AQ7280-01EN
Optical Pulse Measurement (OTDR)
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Index
Sample Interval
The maximum number of sample data points is 256000. The shortest sample interval is determined
by the distance range.
Normal:
The AQ7280 uses the optimum sample interval for the measurement method to
perform measurements.
High Resolution: The AQ7280 uses a sample interval that would result in the greatest number of
data points.
If you use a short sample interval, you can measure for finer changes. However, the data size of the
measured result becomes large.
Attenuation
If large reflections are caused by connectors or by breaks in the optical fiber cable, the waveform
may be saturated. Specify attenuation to prevent the waveform from being saturated.
The attenuations that you can select vary depending on the pulse width, as shown in the following
table.
Pulse Width (Example) Selectable Attenuations
3 ns to 20 ns
0 dB, 2.50 dB, 5.00 dB, 7.50 dB, 10.00 dB, 12.50 dB, 15.00 dB, 17.50 dB
30 ns to 50ns
0 dB, 2.50 dB, 5.00 dB, 7.50 dB, 10.00 dB, 12.50 dB, 15.00 dB, 17.50 dB, 20.00 dB,
22.50 dB
100 ns to 5 µs
0 dB, 2.50 dB, 5.00 dB, 7.50 dB, 10.00 dB, 12.50 dB, 15.00 dB, 17.50 dB, 20.00 dB,
22.25dB, 25.00 dB
10 µs to 20 µs
0 dB, 2.50 dB, 5.00 dB, 7.50 dB, 10.00 dB, 12.50 dB, 15.00 dB, 17.50 dB, 20.00 dB,
22.25dB, 25.00 dB, 27.50 dB, 30.00 dB
Note
• If the distance range or pulse width is set to Auto or if the average method is set to High Resolution, you
cannot select the attenuation.
• If the waveform is saturated, you cannot perform measurements with high sensitivity, so specify a large
value.
• The pulse widths that you can set vary depending on the OTDR unit.
Average Method
• Hi-Speed
In Hi-Speed mode, all sections are measured according to the specified attenuation. If the
specified attenuation value is not appropriate and a large reflection occurs, the waveform for that
section may be saturated.
If reflections are large, the waveform may be saturated.
• Hi-Reflection
In Hi-Reflection mode, the AQ7280 can perform measurements correctly even if large reflections
(excluding extremely large reflections caused by sections of the fiber such as the open end of the
fiber) occur. In Hi-Reflection mode, the AQ7280 sets the optimum attenuation according to the
backscatter level for each section, and performs the measurement. Therefore, the measurement
time is longer than in Hi-Speed mode.
The partitioning of the optical fiber into sections and the specifying of the optimum attenuation
are done automatically.
2.1 Setting the Measurement and Analysis Conditions
